Electro-acoustical warning device



Dec. 26, 1961 L. E. SEPTER ELECTRO-ACOUSTICAL WARNING DEVICE Filed March 20, 1958 2 Sheets-Sheet 1 L. E. Septev BY g w ATTORNEYS Dec. 26, 1961 L. E. SEPTER 3,0

ELECTRO-ACOUSTICAL WARNING DEVICE Filed March 20, 1958 2 Sheets-Sheet 2 60 4719/ Pan 5,2 6TH r/a/v 6' 0 j g; M W12 1 k 074/ Pea/5,2 LIA/6 1N VENTOR L. E Septer H0055 19 6 01/66 3 ATTORNEY? ite 3,9lfi93 Patented Bee. 25, 1961 ice 3,015,093 ELECTRO-ACOUSTICAL WARNiN G DEVHIE Leslie E. Septer, Box 16, Bloomington, Ind. Filed Mar. 20, 1958, Ser. No. 722,736 3 Claims. (Cl. 340-310) This invention relates to electro-acoustical warning devices and more particularly to warning devices for use in an air attack alarm system.

The capability of sudden, massive attack on an entire country by use of long range aircraft and rocket missiles has made it imperative that an adequate warning system be developed and put into operation whereby the entire citizenry may be alerted and warned of an impending or actual attack. It is well known that the use of rocketry and nuclear explosives has reduced the available time for extending such warning to a matter of seconds, and this puts severe limitations as to effectiveness on any warning system or apparatus. Civil Defense tests have conclusively proved that if timely warning is given and simple but effective measures are taken many lives may be saved that would otherwise be lost.

Civil Defense authorities have undertaken to maintain an alarm system which extends to certain key posts throughout the country and to maintain siren and loudspeaker signals in areas of concentrated population for the purposes of warning the general public. The present system, which includes the use of a radio Conelrad frequency, has certain clear limitations, particularly as to total time required for reaching the entire public. The siren signals are reasonably effective only in an area of concentrated population, and if homes and buildings are closed the signal may not be audible. The signal is not effective at all in suburban areas where homes are scattered. In the case of radio and television warning broadcasts designed to reach suburban and country areas, there is only a low percentage of elfectiveness since only part of the sets may be on at a given time, and an attack would undoubtedly be timed to occur during a period when most sets are normally turned off.

It is apparent, therefore, that there is need for a warning signal that would be capable of warning the occupants of each house at any time of the day or night. Such a signal should operate effectively within a very few seconds from the time military and civil defense authorities are aware of the attack. it is necessary that the system and apparatus involved be inexpensive to install and maintain. It is imperative from the economic viewpoint that the apparatus used be low in first cost, so that the signal means may be placed in every home, without regard to the economic status of its occupants, and it is also important that the cost of installing the general system be within the budgets allotted for civil defense.

It has been suggested in the past that the electric power distribution systems now blanketing the entire country are an ideal base for a signal system because the power lines reach into every home, urban, suburban or country, and because power systems are interconnected over large areas.

It is an object of the present invention to provide warning apparatus which may be applied in connection with the power distribution systems now in use, without modification of the systems at either the generating end or the dwelling end, and which is capable of using certain power station control carrier apparatus now in use for other purposes,

A further object is to provide a warning device which may be installed in any home or building by the simple act of plugging it into a standard electrical receptacle and which will be responsive to a carrier signal frequency imposed on the power circuit.

Still another object is to provide a warning device for home or building installations which may be manufactured and sold at a very low cost, so that it may be initially purchased by home owners or replaced without difiiculty when worn or damaged.

A further object is to provide a warning device that consumes a very small amount of operating current, that is reliable, that requires very little maintenance and which may be supplied flexibly in any number to a building without aifecting the characteristics of the power circuit or the load thereon.

Still another object is to provide a warning device that is acoustically very efficicnt for its size and cost and which does not require for its operation any change in the standard sixty cycle frequency of the main power current, nor does it require any temporary break in the main power current.

A further object is to provide a warning unit that is capable of close adjustment to adapt it to variations inthe carrier signal frequency which may occur due to variations in power station signal apparatus or circuit irregularities.

Still another object of the invention is to provide a warning device which may easily be adapted to visual signaling for the hard of hearing, or which with additional structure could be caused to turn on radio and television sets for reception over a Conelrad frequency set aside for civil defense use.

A further object is to provide warning apparatus which is flexibly adjustable to use in other emergency situations, such as hurricanes, cyclones and floods, and which is capable of use during the warning operation to distinguish between the types of emergency.

With the above and other objects in view, as will be presently apparent, the invention consists in general of certain novel details of construction and combinations of parts hereinafter fully described, illustrated in the accompanying drawings and particularly claimed.

in the accompanying drawings like characters of reference indicate like parts in the several views,

FIG. 1 is an exploded, isometric View of the preferred form of warning device taken from the left rear thereof;

FlG. 2 is a longitudinal section taken through the electro-acoustical assembly with the cover removed;

FIG. 3 is a cross-sectional view taken on the line 3-3 of FIG. 2;

FIG. 4- is an isometric view taken from the left front of the casing;

FIG. 5 is a schematic showing of the electrical circuit of the form of PEG. 1;

FIG. 6 is a longitudinal section showing a modification of the warning device;

FIG. 7 is a cross-sectional view taken on line 77 of FIG. 6;

FIG. 8 is a front elevational View of the coil and reed assembly which appears in side view of FIG. 6;

FIG. 9 is an isometric view of the clamping element for the reed;

FIG. 10 is a side elevational view of the modification of FIG. 6;

FIG. 11 is a schematic View of the electrical circuit of the modification of FIG. 6; and

FIG. 12 is a simplified schematic circuit illustrating the principle of the circuit to which the warning devices of the present invention is applied.

Referring to the drawings, in the preferred form the operational parts of the Warning unit are housed in a casing formed of the base 2% and the cover 21. The case 20 telescopes within the cover 21 and indentations 22 are struck inwardly in the cover forming stop means to limit movement of the base 2% into the cover 21. As shown in FIG. 4, the front face of the cover 21 is provided with apertures 23 which permit sound passage from the diaphragm later to be described.

The base 26 is provided with an L-shaped bracket 24 which has an inner face 25 and apertures 26 and which supports the electro-acoustic assembly shown in exploded form in FIG. 1. A pole bracket 2'7 of metal is formed with an inwardly bent end 28, ears 22! extending laterally of the lower end, and apertures 3 in said ears. A second pole bracket 27 of identical form is in opposed relation to the pole bracket 27. Between the lower ends of the pole brackets 27 and 27 are placed two relatively powerful magnets 31 and 31 of Alnico or the like. Between said magnets is clamped the lower end of a reed 32 which extends upwardly, as shown in FIG. 2, between and slightly beyond the spaced ends 23 of the pole brackets. A coil 33 of fine wire is positioned around the reed 32 and occupies the space between the magnets 31 and 31' and the ends 28 and 28. Thin plates 34 and 34' of dielectric material, at the upper and lower ends of the coil 33, are notched as at 35 to receive the pole brackets 27 and 27 and serve as spacers for the assembly.

Adjacent the pole piece 27' is positioned a plate 36 of dielectric material. This plate is provided with spaced apertures 37 and serves as an electrical insulator as well as a spacer for the wiring connections. When assembled, bolts 38 extending through apertures 37, 3%, 30 and 26 clamp the assembly against the face 25 of the bracket 24.

A diaphragm frame 39 is secured to the pole bracket 27, with the blocks 46 serving as spacer blocks. The frame 39 has an outwardly bent lower flange 41, and a reverse bend 43 at its upper end. The free end 43 of the reverse bend is in vertical alignment With the end of the flange 41. The end of the flange 41 and the free end 43 are notched as at 44 and 4 to receive a metal diaphragm 45. This diaphragm 45 is securely fastened at its ends so that it may be strongly stretched. The reverse bend 42 is provided with a threaded aperture 46 and a screw 47 which has its end resting against the leg 4-8 of the reverse bend 42. Apertures 49 in the bight of the bend increase the resilience of the reverse bend and the stretch of the diaphragm 45 may be controlled within limits by the screw 47. Bars 50 serve to space the frame 39 relative to the walls of the cover 21. A wire 51 connects the upper end of the reed 32 to the diaphragm 4'5 and a rib 52 may be used to assist in connecting the said wire to the diaphragm.

Mounted in the rear wall of the cover 21 is a male connector 53 bearing the prongs 54. Leads 55 and 56 extend from the prongs 54, and lead 56 is connected to the end of a pair of condensers 5'7 and 58. The opposite ends of said condensers are connected to the coil lead 59 and the coil lead is fastened to the connector lead 55 at the connection point 61.

The warning device was found to operate with high efficiency when tuned to be resonant to a nominal frequency of range of 708722 cycles per second, although other frequencies could be used as long as they are sufficiently distinct from the 60 cycle power frequency. In the preferred modification, the device constructed was found to have a reliable operation at a nominal frequency 710 cycles per second. The reed 32 is designed to be resonant within the frequency range indicated, and this also is true of the diaphragm 4-5. It was also discovered that the housing 21 should be designed to be resonant to the carrier frequency range. It was found that by tuning all three elements, a higher acoustical efficiency was obtained. The condensers 57 and 58 serve to reduce hum and 60 cycle A.C. signal reproduction.

The second form of the invention, disclosed in FIGS. 6-11, is a somewhat simplified but workable modification.

The device is housed in a base 62 to which is fastened a cover 63. Inset into the base 62 is a male connector 64 of dielectric material, provided with prongs 65. Notches 62 cut in the base provide slots for sound egress.

Secured to the inner wall of the cover 63 by screws 66 is a supporting bracket 67. This bracket has an elongated lower leg 63 and a short upper leg 69. The lower leg 68 carries a coil spool 78 formed of fine wire wound about an armature 71. The armature was found to be more effective when the downwardly and outwardly sloping faces 72 were cut thereon and the ridge formed thereby sloped downwardly from rear to front. A clamping bar 73 ecured by screws to the upper leg '69 is provided with a fine notch 74 in its lower face. A tuned wire reed '75 is clamped by the bar 73 and its position and length is easily adjusted by loosening the screws. It was found desirable to curve the wire 75 slightly downwardly, which substantially improved its vibration characteristics.

Leads '76 and '77 extend from the coil to the prongs '65. A condenser 78 is preferably inserted in the lead 77 to damp burn and reduce 60 cycles A.C. signal re production.

Again, in the second modification the wire reed 75 is tuned to resonance at any selected frequency range which is properly distinct from 60 cycles, but preferably in a range from 708-722 cycles per second.

The housing cover 63 is likewise tuned to this resonance. The result was found to be highly increased acoustical efficiency.

FIG. 12 shows a highly simplified schematic diagram of a typical circuit in which the devices would be used. For purposes of clarity a simple two-wire circuit has been shown. The main power station feeds a 60 cycle current into the main power line and through the branch circuits to houses A and B. House A. has two warning units C and D plugged into the power line receptacles. House B has three units C, D, and E plugged into its receptacles. At the station a signal generator 86 is capable of feeding to the main power line a 2 to 15 volt carrier signal of 708 to 722 cycles per second frequency superimposed upon the main 6O cycle power current. Upon receipt of the attack signal at the main power station the signal generator for the superimposed carrier frequency is applied to the line. The tuned reed 32 of the first form or the wire reed 75 of the modification will vibrate in resonance with the signal current and the sound signal amplified by the diaphragm and cover, or by the cover alone in the modification, Will provide an efiective warning.

In the preferred form of the invention, the diaphragm 45 may be tuned to the exact signal frequency by turning the screw 47. This will stretch or release the diaphragm to change its specific resonance. In the modification, by moving the wire reed 75 under the clamping plate 73, the said reed may be adjusted to the exact signal frequency. The warning devices are continually activated by the 60 cycle power current, but because of their resonance characteristics are not affected thereby. However, when they are reached by the carrier signal current, they respond to said frequency by emitting a clear signal.

While there are herein shown and described the preferred embodiments of the invention, it is nevertheless to be understood that minor changes may be made therein without departing from the spirit and scope of the invention as claimed.

I claim:

1. In a warning device for attachment to a 60 cycle standard power circuit, a casing, a solenoid coil in said casing, an armature for said coil, means for connecting said coil to said power circuit, a reed adapted to be vibrated by an alternating flux in said armature, a tensioned diaphragm in said casing, adjustable means within said casing for supporting said diaphragm at its ends and for stretching it to adjust the tension thereon, a link connecting said diaphragm to said reed, said link being positively connected to said reed and said diaphragm respectively, said reed and said diaphragm being tuned to be resonant only to a carrier signal frequency superimposed on said power circuit.

2. In a Warning device for attachment to a 60 cycle standard power circuit, a casing, a solenoid coil in said casing, an armature for said coil, means for connecting said coil to said power circuit, a reed adapted to be vibrated by an alternating flux in said armature, a C- shaped frame in said casing, a diaphragm supported and stretched between the free ends of said frame, adjustable means within said casing to adjust the amount of stretch imposed on said diaphragm by said frame, a link connecting said diaphragm to said reed, said link being positively connected to said reed and said diaphragm respectively, said reed and said diaphragm being tuned to be resonant only to a carrier signal frequency superimposed on said power circuit.

3. In a warning device for attachment to a 60 cycle standard power circuit, a casing, a solenoid coil in said casing, an armature for said coil, means for connecting said coil to said power circuit, a reed adapted to be vibrated by an alternating flux in said armature, a frame in said casing, said frame having a straight body portion, a bent leg at one end, a deep reverse bend forming a leg at the opposite end, a threaded aperture in one side of said bend, a screw through said aperture having its end bearing against the other side of said bend and its head within said casing, a diaphragm supported and stretched between the said legs, a link connecting said diaphragm to said reed, said link being positively connected to said reed and said diaphragm respectively, said reed and said diaphragm being tuned to be resonant only to a carrier signal frequency superimposed on said power circuit.

References Cited in the file of this patent UNITED STATES PATENTS 1,725,164 Slepian Aug. 20, 1929 2,709,801 Sprague May 31, 1955 2,791,972 Smith May 14, 1957 2,915,743 Stewart Dec. 1, 1959 

